Biosensors are devices that use biochemical reactions to identify and detect various molecules and biochemical analytes. Biosensors are widely used in different life-science applications, ranging from environmental monitoring and basic life science research to Point-of-Care (PoC) in-vitro diagnostics. Biosensors are known to be very sensitive and also extremely versatile in terms of detection and they can detect a small number of almost any kind of molecular structure, once a proper recognition molecule is identified. Example analytes that have been detected using biosensors include DNA and RNA strands, proteins, metabolites, toxins, micro-organisms, and even explosives molecules.
All biosensors, independent of the analyte they are trying to detect, include two key building blocks. One is the molecular recognition layer which is responsible for identifying and/or interacting with and/or reacting with and/or capturing the specific target analyte from the sample. The other is the sensor apparatus which detects and/or quantifies the interactions of the recognition layer with the analyte and provides a measurable output, generally in the form of an electrical signal. The molecular recognition layer typically comprises of carefully engineered and surface-assembled bio-molecules in the form of spotted or synthesized DNA oligonucleotides, aptamers, and antibodies attached to solid surfaces such as glass slides, micro-beads, electrodes, semiconductor materials, or dense polymers while the sensor includes optical-, MEMS- and/or electronics-based transducers connected to a low-noise circuit.
So far, there have been many detection methods that have been adopted in biosensor systems. A detection method is generally defined as the specific type of physiochemical mechanism designed into the molecular recognition layer, analytes, and the interaction environments that make the identification of the specific target analytes possible. The most widely used detection methods are different types of optical (e.g., fluorescence, bioluminescence) and electro-analytical (e.g., potentiometric, amperometric, impedimetric). It is also common to classify biosensors based on their detection method (e.g., in bioluminescence-based biosensors, the interaction of the analyte and probes results in a bioluminescence phenomenon which is detected by a specific sensor with a transducer sensitive to bioluminescence signals).
Currently, it has been difficult to build biosensors, such as optical biosensors, using Complementary Metal-Oxide Semiconductor (CMOS) processes thereby preventing the reduction of the bulkiness, complexity, etc. of the optical biosensors. Furthermore, there is not currently a biosensor array architecture that includes optical biosensors that overcome such limitations.